Electrophilic trifluoromethylating reagents

Electrophilic trifluoromethylation reagents can be generated from the treatment of trifluoromethyl biphenyl sulfoxides with Tf20. These reagents will react with a wide range of nucleophiles including carbanions, aromatics, silyl enol ethers, thiolates, and phosphines (eq 90). ... 

While Yu et al. [15] reported the palladium-catalyzed ortho trifluoromethylation of arenes with an electrophilic trifluoromethylation reagent (Scheme 19.9), Liu and coworkers [69] developed a nondirected C-H trifluoromethylation method using the nucleophilic Ruppert-Prakash (TMSCFj) reagent (Scheme 19.43). Thus, indoles underwent trifluoromethylation in moderate yields at the C-2 position or, when the C-3 position was free, at the C-3 position in the presence of a Pd /bis-oxazoline catalyst, cesium fluoride, PhI(OAc)2 as the stoichiometric oxidant, and TEMPO as a radical trap. Similar to Yu s method, the mechanism was proposed to involve the formation of an Ar-Ph -CEj intermediate that reductively eliminates to form the Ar-CFj bond. 

Liu T, Shen Q (2011) Copper-catalyzed trifluoromethylatimi of aryl and vinyl boronic acids with an electrophilic trifluoromethylating reagent. Org Lett 13 2342-2345. doi 10.1021/ O12005903... 

Trifluoromethylation. (5)-(Trifluoromethyl)diphenylsulfo-nium triflate is used as an electrophilic trifluoromethylation reagent. The reactivity can be modified through the introduction of different substituents into the ring. When there is an electron-withdrawing group present on the benzene ring, the electrophilic trifluoromethylation ability is greatly enhanced. ... 

Scheme 13 Generation of the CF3 radical from electrophilic trifluoromethylating reagents through SET photoredox processes...

SCHEME 26.22. Reaction of lithium acetylide with electrophilic trifluoromethylating reagent. 

SCHEME 26.25. Copper-catalyzed trifluoromethylation using an electrophilic trifluoromethylating reagent. 

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